Temperature sensing device

ABSTRACT

A temperature-sensing device for hot gases which consists of a pneumatic oscillator that includes an inlet channel, a diffusor, a wedge projecting into the diffusor, which is adjoined by two outlet channels from which one return channel each leads back to the nearest side of the diffuser inlet, whereby each outlet channel has at least half the length of a return channel and passes over into a throttle channel whose cross-sectional area corresponds at least to half the cross-sectional area of the inlet channel of the diffusor.

Unlted States Patent 1 1 1111 3,805,614 Walliser Apr. 23, 1974 [54] TEMPERATURE SENSING DEVICE 3,667,297 6/1972 Vondell 73/339 A 3,185,166 5/1965 Horton etal. 137/815 [75] Invent Gerhard wa'blmgem 3,587,603 6/1971 Bailey 73/357 Germany 3,513,706 5/1970 Berrey 73/357 [73] Assignee: Daimler-Benz Aktiengesellschaft, I

S pUm -kh i Germany Primary Examiner--R1chard C. Queisser Assistant Examiner-Daniel M. Yasich [22] Flled: 1971 Attorney, Agent, or Firm-Craig and Antonelli [21] App]. No.: 192,502

[57] ABSTRACT [30] Foreign Application Priority Data A temperature-sensing device for hot gases which conom. 30, 1970 Germany 2053320 Sists Of a Pneumam Oscillator that includes an inlet channel, a diffuser, a wedge projecting into the diffu- 52 U.S. c1. 73/339 A, 137/826 sor, which is adjoined y two outlet channels from 51 Im. c1. G01k 11/26 which one return channel each leads back to the near- [58] Field of Search 73/339 R, 357, 339 A; est side of the diffuser inlet, whereby each outlet 137/ 15 32 channel has at least'half the length of a return channel and passes over into a throttle channel whose cross- 5 Refe en e Ci d sectional area corresponds at least to half the cross- UNITED STATES PATENTS sectional-area of the inlet channel of the diffuser. 3,707,979 1/1973 Zoerb 73/339 A X 13 Claims, 2 Drawing Figures PATENTEDAPR 2 1914 3.805614 TEMPERATURE SENSING DEVICE The present invention relates to a temperaturesensing device for hot gases, which consists of a pneumatic oscillator, having an inlet channel, a diffusor, and a wedge projecting into the same, which is adjoined by two outlet channels, from which one return channel each leads to the nearest side of the diffusor inlet.

If one feeds a gas to the diffusor of such an oscillator, whose channel walls have a rectangular cross section, then the flow normally abuts in a stable manner at one of the two side walls of the diffusor due to slight asymmetries conditioned by the manufacture. An oscillating, i.e., a constant jumping of the flow and therewith an alternate abutment at one of the two diffusor walls, is effected by the return channels. For example, a flow abutting at the left diffusor wall initiates a pulse at the diffusor inlet by way of the return line branching off from the corresponding outlet channel which leads to a jumping of the flow and to the abutment thereof at the right diffusor wall. Thereafter, the flow jumps in a similar manner again to the left diffusor wall where the process repeats itself. The frequency of the thusresulting auto-oscillation depends, in a well-known manner, on the sound velocity of thegases and therewith indirectly on the temperature thereof. For this reason, the frequency represents a measurement for the temperature of the gases and can be utilized for the de termination thereof.

The frequency of the oscillations, in addition to being influenced by the sound velocity, is also influenced by the pressure of the gases so that deviations from the actual value result in the indication of the gas temperature dependent on frequency. The present invention is concerned with the task to provide a temperaturesensing device for hot gases in which the pressure influence on the oscillator frequency is practically eliminated. This is realized according to the present invention in that each outlet channel has at least one-half the length of a return channel and passes over into a throttle channel whose cross-sectional area corresponds to at least half the cross-sectional area of the inlet channel of the diffusor. As a result thereof, the oscillations of the oscillator are generated, notby the feedback alone as is the case with a'pure feedback oscillator, but also by the wedge as ,is'the case with a flue tone oscillator. The return channels effect'an amplification of the oscillatory amplitudes and a starting of the oscillations at a small input pressure. The pressure influence is eliminated and thus an undisturbed sinusoidal oscillation picture is produced According to a further feature of the present invention, the throttle channel is constructed as bore in a connecting member adapted to be screwed into the housing of the oscillator. This permits, in addition to an accurate and inexpensive manufacture of the throttle channel, also a simple installation or exchange thereof.

Accordingly, it is an object of the present invention to provide a temperature-sensing device whichavoids by simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a temperature-sensing device of the aforementioned type which practically completely eliminates the influence of pressure on the measurement results.

A further object of the present invention resides in a temperature detecting device for hot gases which proin a temperature feeler which produces oscillations forming pure sinusoidal waves when-reproduced, for

example, on an oscilloscope.

Another object of the present invention resides in a temperature-sensing device which can be manufactured in a relatively simple manner andpermits ready exchange of the parts thereof.

These and other objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein:

FIG. 1 is a cross-sectional view through a temperature-sensing device of the present invention, taken along line I---[ of FIG. 2; and

FIG. 2 is a cross-sectional view taken along line 11-" of FIG. 1.

Referring now to the drawing wherein like reference numerals are used throughout the two views to designate like parts, a pneumatic oscillator serves as a temperature-sensing device which essentially consists of a two-partite housing 11 and 11 in which are arranged an inlet channel 12, a diffusor 13, two outlet channels 14 and 15 and two return channels 16 and 17. All of the channels 12 to 17, inclusive of the diffusor 13, have a rectangular cross section. A wedge 18 projects into the symmetrically constructed diffusorl3 which separates the outlet channels 14 and 15 from one another. The return channels. 16 and 17 branch off from the side of a respective outlet channel 14 and 15 opposite the wedge 18 and terminate atmutually opposite places in an inletchannel19 of the diffusor 13. A connecting member 20 for the inlet channel 12 and. connecting members 21 and 22 for the outlet channels 14 and 15 are screwed into the housing 11'. Furthermore, a quartz crystal pressure receiver 23 is connected to the housing 11 which is connected by way of a channel or duct 24 with the outlet channel 14. A cable 25 leads to an indicating apparatus (not shown), for example, to an oscillograph. The measurement values, in lieu thereof, may also be fed to a control device of any known construction. However, it is also possible to further process the pneumatic pressure pulses of the oscillator directly. v

One throttle channel 26 is arranged in each of the connecting members 21 and 22. The cross-sectional area of the throttle channel 26 constructed as a bore corresponds approximately to half the cross-sectional surface area of the inlet channel 19 of the diffusor 13. As a result of the presence of the throttle channels 26, the outlet channels 14 and 15 in cooperation with the inlet channel 19 of the diffusor 13 form a nearly closed resonator channel in which is formed an average pressure. This average pressure is determined essentially by the free cross-sectional area of the throttle channels 26 and of the inlet channel 19 of the diffusor 13. Experiments have indicated that the-pressure influence on the frequency of the oscillations can be kept negligibly small with a required minimum length of the outlet channels 14 and 15 and the indicated ratio of crosssectional areas, above. A very accurate, pressureindependent determination of the temperature of the my copending hot gases results thereby from the temperature sensing device constructed as pneumatic Oscillator.

in lieu of accommodating the throttle channels in the connecting members, the throttle channels may also be arranged directly in the housing. For example, with an oscillator consisting of a lamella packet as disclosed in application entitled Temperature Peeler", Ser. No. 191,481, throttle channels with rectangular cross section together with the other channels may be formed by etching the individual lamella and by the subsequent soldering together with the use of a high temperature solder in a vacuum furnace.

While I have shown and described only one embodiment in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications -as are encompassed by .the scope of the appended claims. 'What I claim is:

l. A temperature-sensing device for hot gases of the type in which temperature sensing is substantially independent of gas pressure, said device including a pneumatic oscillator including a housing having an inlet channel means,v a diffuser means with a diffuser inlet leading from said inlet channel means into said diffuser means, and a wedge projecting into the diffuser means, adjoined by two outlet channel means leading from said diffuser means in which from each outlet means a return channel means leads to respective proximate sides of the diffuser inlet, characterized in that each outlet channel means has a length of at least half the length of a return channel means and leads into a throttle channel means whose cross-sectional area corresponds to at least half of the cross-sectional area of the diffuser inlet.

hot gases according to claim 1, characterized in that the throttle channel means are constructed as bores in connecting means screwed into the housing of the oscillator.

3. A temperaturesensing.device according to claim 2, characterized in that each return channel means leads to the nearest side of the diffuser inlet.

4. A temperature-sensing device with housing means according to claim 1, characterized in that the throttle channel means are arranged directly in the housing means for the oscillator.

2. A temperature-sensing device with a housing for 5. A temperature-sensing device according to claim 4, characterized in that the throttle channel means are formed by component parts of the housing means.

6. A temperature-sensing device according to claim 5, characterized in that each return channel means leads to the nearest side of the diffuser inlet.

7. A temperature-sensing device according to claim 1, further comprising means for detecting oscillation frequencies of gases oscillating in said pneumatic oscillater.

8. A temperature-sensing device for hot gases of the type in which temperature sensing is substantially independent of gas pressure, said device comprising a pneumatic oscillator including a housing havinga first and second part, said first part having diffuser means having diffuser inlet channel means, two outlet channel means extending from said diffuser means, return channel means extending from each outlet channel means to respective proximate sides of the diffuser inlet channel means, and throttle channel means in said second part leading from said outlet channel means,

wherein the relative dimensions of the outlet channelz means to the return channel means and of the throttle channel means to the diffuser inlet channel means are such that oscillation frequencies of gases oscillating in said pneumatic oscillator are independent of the pressure of the gases.

9. A temperature-sensing device according to claim 8, wherein said pneumatic oscillator further includes inlet channel means leading to said diffuser means and wedge means projecting into said diffuser means and separating said two outlet channel means.

10. A temperature-sensing device according to claim 8, wherein each outlet channel means is at least onehalf the length of the return channel means and said throttle means has a cross-sectional area corresponding to at least half the cross-sectional area of the diffuser inlet channel means. I

11. A temperature-sensing device according to claim 8, further comprising means for detecting oscillation frequencies of gases oscillating in said pneumatic oscillater.

12. A temperature-sensing device according to claim 11, whereinsaid means for detecting includes a quartz crystal pressure receiver connected by a channel to said outlet channel means.

13. A temperature sensing device according to claim 8, wherein each return channel means leads to the nearest side of the diffuser inlet.

l i l l i 

1. A temperature-sensing device for hot gases of the type in which temperature sensing is substantially independent of gas pressure, said device including a pneumatic oscillator including a housing having an inlet channel means, a diffusor means with a diffusor inlet leading from said inlet channel means into said diffusor means, and a wedge projecting into the diffusor means, adjoined by two outlet channel means leading from said diffusor means in which from each outlet means a return channel means leads to respective proximate sides of the diffusor inlet, characterized in that each outlet channel means has a length of at least half the length of a return channel means and leads into a throttle channel means whose cross-sectional area corresponds to at least half of the cross-sectional area of the diffusor inlet.
 2. A temperature-sensing device with a housing for hot gases according to claim 1, characterized in that the throttle channel means are constructed as bores in connecting means screwed into the housing of the oscillator.
 3. A temperature-sensing device according to claim 2, characterized in that each return channel means leads to the nearest side of the diffusor inlet.
 4. A temperature-sensing device with housing means according to claim 1, characterized in that the throttle channel means are arranged directly in the housing means for the oscillator.
 5. A temperature-sensing device according to claim 4, characterized in that the throttle channel means are formed by component parts of the housing means.
 6. A temperature-sensing device according to claim 5, characterized in that each return channel means leads to the nearest side of the diffusor inlet.
 7. A temperature-sensing device according to claim 1, further comprising means for detecting oscillation frequencies of gases oscillating in said pneumatic oscillator.
 8. A temperature-sensing device for hot gases of the type in which temperature sensing is substantially independent of gas pressure, said device comprising a pneumatic oscillator including a housing having a first and second part, said first part having diffusor means having diffusor inlet channel means, two outlet channel means extending from said diffusor means, return channel means extending from each outlet channel means to respective proximate sides of the diffusor inlet channel means, and throttle channel means in said second part leading from said outlet channel means, wherein the relative dimensions of the outlet channel means to the return channel means and of the throttle channel means to the diffusor inlet channel means are such that oscillation frequencies of gases oscillating in said pneumatic oscillator are independent of the pressure of the gases.
 9. A temperature-sensing device according to claim 8, wherein said pneumatic oscillator further includes inlet channel means leadinG to said diffusor means and wedge means projecting into said diffusor means and separating said two outlet channel means.
 10. A temperature-sensing device according to claim 8, wherein each outlet channel means is at least one-half the length of the return channel means and said throttle means has a cross-sectional area corresponding to at least half the cross-sectional area of the diffusor inlet channel means.
 11. A temperature-sensing device according to claim 8, further comprising means for detecting oscillation frequencies of gases oscillating in said pneumatic oscillator.
 12. A temperature-sensing device according to claim 11, wherein said means for detecting includes a quartz crystal pressure receiver connected by a channel to said outlet channel means.
 13. A temperature sensing device according to claim 8, wherein each return channel means leads to the nearest side of the diffusor inlet. 